Traditional remote control devices for Audio/Visual (AV) devices, such as televisions (TVs), receivers, tuners, amplifiers, video cassette recorders (VCRs), digital video disc (DVD) players, etc., use infrared (IR) light to communicate simple commands to the devices being controlled. There are few standards for remote control IR signaling, modulation, or protocols, and those standards that do exist are not widely used. As a result, separate remote controls may be required for the TV, VCR, DVD player, receiver, and Set-Top Box (STB) found in a typical living or family room. This is clearly cumbersome and results in clutter—in this case, five remote controls on the coffee table.
In an attempt to ameliorate this situation, “universal” and “learning” remote controls have been developed. A number of suppliers have researched the IR signaling, modulation, protocols, and commands used by almost every AV product made in recent years and created a compressed format for storing all of the IR information in a database. A universal remote control stores the entire database (or perhaps a subset representing the most common AV devices in a particular market) of IR information and allows the user to program the universal remote control to control all the AV devices in a room. A simple remote control designed to control only one specific AV product can be implemented using a very low cost 4- or 8-bit microcontroller unit (MCU) with as little as one kilobyte (1 kB) of read-only memory (ROM). A universal remote control, however, requires an MCU with 24-48 kB of ROM, depending on how comprehensive the library is. This substantially increases the cost of the universal remote control.
A learning remote control takes a different approach. Rather than storing an entire database of codes, a learning remote control has an IR receiver. The learning remote control can receive the IR signals sent by another IR remote control. Thus, the learning remote control can be programmed to “learn” the IR commands sent by another IR remote control and control any or all of the AV devices in a system controlled by another IR remote control.
In practice, many universal remote controls also include a learning feature. These universal remote controls typically include a subset of the full code library to allow programming the most common devices; less common devices can be controlled using the learning feature of the universal remote control.
One very significant drawback of both universal and learning remote controls is the difficulty of programming them. Hence, a user must refer to an instruction manual for programming instructions. Although a remote control has many buttons, the only commonly available method of user feedback is a single light-emitting diode (LED). A typical programming sequence for a universal remote control comprises the following steps:
1. The user presses 1 or a device mode button for several seconds. Typically, a universal remote control includes a plurality of device mode buttons (e.g., CABLE, TV, VCR and OTHER) corresponding to the different AV devices to be controlled. To program the universal remote control to control a TV, for example, the user presses the TV button on the remote control.
2. The LED starts blinking to indicate programming mode.
3. To determine the IR code required to program the universal remote control to control the user's TV, the user refers to a large table of AV Products in the instruction manual. The IR code table, often comprising many pages, provides a listing of TV manufacturers, model numbers, and a 3- to 6-digit number.
4. The user enters the 3- to 6-digit number.
5. The user repeats steps (1)-(4) for each AV device to be controlled by the universal remote control.
6. The user presses 1 or the device mode button for several seconds.
7. The LED stops blinking to indicate that programming is complete.
Programming a learning remote control is even more complex. The procedure for entering learning mode typically comprises the same steps as that described above for entering programming mode. The user must position the remote control being learned from (the “teaching” remote control) in front of the remote control being taught (the learning remote control) so that the teaching remote control's IR transmitter is directly facing the learning remote control's IR receiver. The user then presses the VOLUME UP button, for example, on the learning remote control, followed by pressing the VOLUME UP button on the teaching remote control. When the learning remote control has received the signals from the teaching remote control, the LED on the learning remote control may blink to indicate to the user that the learning operation for that button has been completed. This process is then repeated for every button that is to be learned. In some cases, if the learning remote control supports multiple AV devices on the same button (e.g., the same PLAY button supports either a DVD or a VCR), then the whole process will be repeated for each AV device in the system, so that the PLAY button will issue a different IR signal depending on whether the DVD or the VCR is selected.
Clearly, these programming processes are not user-friendly. They are time consuming, confusing, and rely on having the instruction manual in hand. As a result, many users do not bother to program their universal remote controls; and many of those who bother, program only a few main features (e.g., PLAY, STOP, VOLUME UP, ENTER CHANNEL) rather than the full control set for every device.
IR is far from an ideal means of controlling AV devices. A positive feature of IR is its very low cost. However, one drawback is that IR requires line of sight between the remote control and the device being controlled. Thus, an IR remote control cannot be used to control devices inside a cabinet with a closed non-glass door. It also places limitations on the positioning of the user's furniture relative to the sitting/viewing position and the location of the equipment, as IR requires that there be no obstruction between the remote control and the device being controlled. Many IR remotes also have distance limitations such that you often can not control things from across a large room. Another drawback is that IR requires large batteries, as the IR LED used to transmit is typically driven with up to 1 A of current. In addition, the data rate is very slow—so slow that even button presses (a few Hz at most) incur a noticeable delay if a number of the button presses are sent consecutively, for example, when pressing VOLUME UP, VOLUME UP, . . . , VOLUME UP to increase the volume to a desired level.
A radio frequency (RF) remote control would be desirable. No line of sight would be required, a greater distance could be covered, much smaller batteries could be used, and more interactive features could be supported (for example, a mouse-like cursor control feature for more sophisticated AV applications). For these reasons and others, RF remote controls have begun to increase in popularity. However, one disadvantage of an RF remote control is that it cannot be a “universal” or “learning” remote control.
Today, the most common RF remote controls are supplied with Cable, Satellite, Digital Terrestrial or Internet Protocol TV (IPTV) Set-Top Boxes. Many STB suppliers would like to offer dual mode RF and IR remote controls, allowing users to have “the best of both worlds.” Such dual mode remote control would have been prohibitively expensive until recently, when the only low cost (less than 1) RF technologies were very simple one-way systems using unlicensed RF bands such as 49 and 433 MHz. These RF technologies were very low data rate (typically, less than 10 kbps) and were not available worldwide, but had relatively good range. In recent years, following the worldwide adoption of a 2.4 GHz unlicensed band, a number of very low cost, two-way, highly integrated radio integrated circuits (ICs) have become available, offering medium range and supporting data rates of up to 1 Mbps.
Thus, a low-cost dual mode IR and RF remote control that greatly simplifies programming the “learning” and “universal” capabilities is desirable.